Methods an apparatus for backhaul and access link scheduling in integrated access and backhaul network and synchronized networks

ABSTRACT

A method, an apparatus, and a computer program product for wireless communication are provided in which a scheduling entity determines a first direction of a backhaul link traffic between a first scheduling entity and a second scheduling entity, and determines a second direction of an access link traffic between the scheduling entity and a user equipment (UE) based on the first direction of the backhaul link traffic to reduce potential interference caused by the access link traffic. The scheduling entity transmits or receives the access link traffic in the second direction utilizing at least one of a same transmission resource of the backhaul link traffic. Other aspects, embodiments, and features are also claimed and described.

PRIORITY CLAIM

This application claims priority to and the benefit of provisionalpatent application No. 62/209,146 filed in the United States Patent andTrademark Office on Aug. 24, 2015, the entire content of which isincorporated herein by reference as if fully set forth below in itsentirety and for all applicable purposes.

TECHNICAL FIELD

The technology discussed below relates generally to wirelesscommunication systems, and more particularly, backhaul and access linktraffic scheduling in wireless communication networks. Embodiments canprovide and enable techniques for scheduling data communications inintegrated access and backhaul integrated arrangements for efficientspectrum utilization, improved network throughput, and continuedenhanced user experience.

INTRODUCTION

Multiple access technologies have been adopted in varioustelecommunication standards to enable different wireless devices tocommunicate on a peer-to-peer, municipal, national, regional, and evenglobal level. A wireless communication network may include one or morescheduling entities each communicating with one or more subordinateentities. A communication connection or link between two schedulingentities may be referred to as a backhaul link (or backhaul), and acommunication connection or link between a scheduling entity and asubordinate entity may be referred to as an access link. In general, thebackhaul link and the access link utilize different transmissionresources for uplink and/or downlink communication such thatinterference may be avoided or reduced. Such wireless communicationnetwork may be called a non-integrated access and backhaul systembecause the access link and the backhaul link are assigned or allocateddifferent transmission resources.

BRIEF SUMMARY OF SOME EXAMPLES

The following presents a simplified summary of one or more aspects ofthe present disclosure, in order to provide a basic understanding ofsuch aspects. This summary is not an extensive overview of allcontemplated features of the disclosure, and is intended neither toidentify key or critical elements of all aspects of the disclosure norto delineate the scope of any or all aspects of the disclosure. Its solepurpose is to present some concepts of one or more aspects of thedisclosure in a simplified form as a prelude to the more detaileddescription that is presented later.

Aspects of the present disclosure relate to an integrated access andbackhaul (IAB) system and methods for operating an IAB system. In an IABsystem, an access link between a scheduling entity and a subordinateentity, and a backhaul link between scheduling entities, may utilize thesame transmission resource for uplink and/or downlink communication.

In one aspect, the disclosure provides a method of wirelesscommunication operable at a scheduling entity. The scheduling entitydetermines a first direction of a backhaul link traffic between a firstscheduling entity and a second scheduling entity; determine a seconddirection of an access link traffic between the scheduling entity and auser equipment (UE) based on the first direction of the backhaul linktraffic. The scheduling entity transmits or receives the access linktraffic in the second direction utilizing at least one of a sametransmission resource of the backhaul link traffic.

Another aspect of the disclosure provides a scheduling entity forwireless communication. The scheduling entity includes means fordetermining a first direction of a backhaul link traffic between a firstscheduling entity and a second scheduling entity. The scheduling entityincludes means for determining a second direction of an access linktraffic between the scheduling entity and a user equipment (UE) based onthe first direction of the backhaul link traffic. The scheduling entityfurther includes means for transmitting or receiving the access linktraffic in the second direction utilizing at least one of a sametransmission resource of the backhaul link traffic.

Another aspect of the disclosure provides a computer program productthat includes a computer-readable medium comprising computer executablecode for causing a scheduling entity to perform various functions. Theexecutable code causes a scheduling entity to determine a firstdirection of a backhaul link traffic between a first scheduling entityand a second scheduling entity. The executable code causes thescheduling entity to determine a second direction of an access linktraffic between the scheduling entity and a user equipment (UE) based onthe first direction of the backhaul link traffic. The executable codefurther causes the scheduling entity to transmit or receive the accesslink traffic in the second direction utilizing at least one of a sametransmission resource of the backhaul link traffic.

Another aspect of the disclosure provides a scheduling entity forwireless communication. The scheduling entity includes a communicationinterface configured for wireless communication, a memory stored withexecutable code, and a processing system operatively coupled to thecommunication interface and memory. The processing system is configuredby the executable code to: determine a first direction of a backhaullink traffic between a first scheduling entity and a second schedulingentity; determine a second direction of an access link traffic betweenthe scheduling entity and a user equipment (UE) based on the firstdirection of the backhaul link traffic; and transmit or receive theaccess link traffic in the second direction utilizing at least one of asame transmission resource of the backhaul link traffic.

These and other aspects of the invention will become more fullyunderstood upon a review of the detailed description, which follows.Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary embodiments of thepresent invention in conjunction with the accompanying figures. Whilefeatures of the present invention may be discussed relative to certainembodiments and figures below, all embodiments of the present inventioncan include one or more of the advantageous features discussed herein.In other words, while one or more embodiments may be discussed as havingcertain advantageous features, one or more of such features may also beused in accordance with the various embodiments of the inventiondiscussed herein. In similar fashion, while exemplary embodiments may bediscussed below as device, system, or method embodiments it should beunderstood that such exemplary embodiments can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a hardware implementationfor an apparatus employing a processing system in accordance with anaspect of the disclosure.

FIG. 2 is a diagram illustrating a network architecture employingvarious apparatuses in accordance with an aspect of the disclosure.

FIG. 3 is a diagram illustrating an example of an access network inaccordance with an aspect of the disclosure.

FIG. 4 is a diagram illustrating an example of a scheduling entity and asubordinate entity in accordance with an aspect of the disclosure.

FIG. 5 is a diagram illustrating an example of an integrated access andbackhaul (IAB) network in accordance with an aspect of the disclosure.

FIG. 6 is a diagram illustrating an example of a time division duplexing(TDD) frame structure in accordance with an aspect of the disclosure.

FIG. 7 is a diagram illustrating two frame structures for opportunisticaccess link or backhaul scheduling in accordance with some aspects ofthe disclosure.

FIG. 8 is a diagram illustrating two examples of synchronized IABscheduling in accordance with some aspects of the disclosure.

FIG. 9 is a diagram illustrating two examples of cross-synchronized IABscheduling in accordance with some aspects of the disclosure.

FIG. 10 is a flow chart illustrating an opportunistic access linkscheduling method operable in an IAB wireless network in accordance withan aspect of the disclosure.

FIG. 11 is a flow chart illustrating a method for determining thebackhaul traffic direction between scheduling entities in accordancewith an aspect of the disclosure.

FIG. 12 is a flow chart illustrating a method for determining anopportunistic access link traffic direction between a scheduling entityand a user equipment in accordance with an aspect of the disclosure.

FIG. 13 is a flow chart illustrating a method of opportunistic accesslink transmission in accordance with an aspect of the disclosure.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Aspects of the present disclosure relate to access link and backhaulscheduling in a synchronized network or an integrated access andbackhaul (IAB) system. An exemplary IAB system includes a number ofscheduling entities that control wireless access to associatedsubordinate entities. Examples of scheduling entities include Node B,eNB, base stations, and access points. Examples of subordinate entitiesinclude various wireless devices such as a user equipment (UE) and anaccess terminal. In some examples, the same device may be configured toinclude the functionalities of both a scheduling entity and asubordinate entity. Other non-limitation examples of the schedulingentity and subordinate entity include set-top boxes, routers, cablemodems, digital subscriber line (DSL) modems, home appliances (e.g.,oven, refrigerator, dishwasher, washer, dryer, television, securitycamera, home entertainment system, etc.), entertainment devices,industrial equipment, medical devices, network gateway devices, andInternet-of-Thing (IoT)/Internet-of-Everything (IoE) devices. Ascheduling entity assigns, allocates, configures, and/or schedulesnetwork resources for supporting, maintaining, and/or establishingcommunication with one or more associated subordinate entities.

In some aspects of the disclosure, scheduling entities may include macrobase stations and pico base stations. A typical heterogeneous networkincludes a higher power cell and a lower power cell. The high power cellmay be referred to as macro cell, and the lower power cell may bereferred to as a micro or small cell (or aka pico, femto, micro, etc.)cell. The macro cell is served by a base station (macro base station)transmitting with higher power than a base station (pico base station)serving the pico cell. A macro base station generally has a largercoverage area than that of a pico base station. Pico base stations aretypically used to extend coverage to a small area such an indoor areawhere the signals of the macro cell cannot penetrate well, or to addnetwork capacity in areas with high service demands. Cell sizing can bedone according to system design as well as component constraints.

In some embodiments as discussed here, a communication link orconnection between two scheduling entities (e.g., a macro base stationand a pico base station) may be called a backhaul or backhaul link. Acommunication link between a scheduling entity (e.g., a base station)and a subordinate entity (e.g., user equipment) may be called an accesslink. In an IAB system, the access link and the backhaul may be assignedthe same transmission resource such as time slots and frequency spectrumwhen the access link or backhaul is opportunistically scheduled. Moredetail of opportunistic scheduling is described with the examples below.

Several aspects of telecommunication systems are presented below withreference to various apparatuses and methods. These apparatuses andmethods will be described in the following detailed description andillustrated in the accompanying drawing by various blocks, modules,components, circuits, steps, processes, algorithms, procedures, etc.(collectively referred to as “elements”). These elements may beimplemented using electronic hardware, computer software, firmware, codeor any combination thereof. Whether such elements are implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system.

FIG. 1 is a diagram illustrating an example of a hardware implementationfor an apparatus 100 employing a processing system 114. In accordancewith various aspects of the disclosure, an element, or any portion of anelement, or any combination of elements may be implemented with aprocessing system 114 that includes one or more processors 104. Forexample, the apparatus 100 may be a subordinate entity (e.g., userequipment (UE)) as illustrated in any one or more of FIGS. 2-5, 8,and/or 9. In another example, the apparatus 100 may be a schedulingentity (e.g., a macro base station or a pico base station) asillustrated in any one or more of FIGS. 2-5, 8, and/or 9. Examples ofprocessors 104 include microprocessors, microcontrollers, digital signalprocessors (DSPs), field programmable gate arrays (FPGAs), programmablelogic devices (PLDs), state machines, gated logic, discrete hardwarecircuits, and other suitable hardware configured to perform the variousfunctionality described throughout this disclosure. That is, theprocessor 104, as utilized in an apparatus 100, may be used to implementany one or more of the processes and procedures described below andillustrated in FIGS. 10-13.

One or more processors 104 in the processing system 114 may executesoftware (executable software or code). Software shall be construedbroadly to mean instructions, instruction sets, code, code segments,program code, programs, subprograms, software modules, applications,software applications, software packages, routines, subroutines,objects, executables, threads of execution, procedures, functions, etc.,whether referred to as software, firmware, middleware, microcode,hardware description language, or otherwise. The software may reside ona computer-readable medium 106.

The computer-readable medium 106 may be a non-transitorycomputer-readable medium. A non-transitory computer-readable mediuminclude, by way of example, a magnetic storage device (e.g., hard disk,floppy disk, magnetic strip), an optical disk (e.g., compact disk (CD),digital versatile disk (DVD)), a smart card, a flash memory device(e.g., card, stick, key drive), random access memory (RAM), read onlymemory (ROM), programmable ROM (PROM), erasable PROM (EPROM),electrically erasable PROM (EEPROM), a register, a removable disk, andany other suitable medium for storing software and/or instructions thatmay be accessed and read by a computer. The computer-readable medium maybe resident in the processing system, external to the processing system,or distributed across multiple entities including the processing system.The computer-readable medium may be embodied in a computer-programproduct. By way of example, a computer-program product may include acomputer-readable medium in packaging materials. Those skilled in theart will recognize how best to implement the described functionalitypresented throughout this disclosure depending on the particularapplication and the overall design constraints imposed on the overallsystem.

In this example, the processing system 114 may be implemented with a busarchitecture, represented generally by the bus 102. The bus 102 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 114 and the overall designconstraints. The bus 102 links together various circuits including oneor more processors (represented generally by the processor 104), amemory 105, and computer-readable media (represented generally by thecomputer-readable medium 106). The bus 102 may also link various othercircuits such as timing sources, peripherals, voltage regulators, andpower management circuits, which are well known in the art, andtherefore, will not be described any further. A bus interface 108provides an interface between the bus 102 and a transceiver 110. Thetransceiver 110 provides a means for communicating with various otherapparatus over a transmission medium. In some examples, the transceiver110 may include one or more transmitters and/or receivers, and otherknown circuits in the art. Depending upon the nature of the apparatus, auser interface 112 (e.g., keypad, display, speaker, microphone,joystick, touchscreen, touchpad, gesture sensor) may also be provided.

The processor 104 may be configured to implement or perform variousfunctions, procedures, and processes. In one aspect of the disclosure,the processor 104 may include a backhaul traffic block 120, an accesslink traffic block 122, and an integrated access and backhaul (IAB)block 124. The processor 104 may execute a traffic scheduling codestored at the computer-readable medium 106 to configure the backhaultraffic block 120, access link traffic block 122, and IAB block 124, toperform the opportunistic access link/backhaul traffic schedulingoperations described in relation to FIGS. 10-13. For example, thebackhaul traffic block 120 may be configured by a backhaul traffic code130 to determine the data traffic direction (e.g., downlink and/oruplink) between two scheduling entities (e.g., a macro base station anda pico base station). The access link traffic block 122 may beconfigured by an access link traffic code 132 to determine the datatraffic direction (e.g., downlink and/or uplink) between a schedulingentity and a subordinate entity (e.g., a pico base station and a UE).The IAB block 124 may be configured by an IAB code 134 to utilize atransceiver 110 to opportunistically transmit and/or receive access linkdata traffic at a scheduling entity (e.g., a pico base station) in adirection determined by the access link traffic block 122 utilizing thesame transmission resource (e.g., time and frequency resources) of thebackhaul traffic.

The processor 104 is also responsible for managing the bus 102 andgeneral processing, including the execution of software stored on thecomputer-readable medium 106. The software, when executed by theprocessor 104, causes the processing system 114 to perform the variousfunctions described below for any particular apparatus. Thecomputer-readable medium 106 may also be used for storing data that ismanipulated by the processor 104 when executing software.

In some aspects of the present disclosure, an IAB system may beimplemented with a network including some features of a Long TermEvolution (LTE) network. FIG. 2 is a diagram illustrating an LTE networkarchitecture 200 employing various apparatuses (an LTE network is shownfor illustrative purposes as other network types can be utilized). TheLTE network architecture 200 may be referred to as an Evolved PacketSystem (EPS) 200. The EPS 200 may include one or more user equipment(UE) 202, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)204, an Evolved Packet Core (EPC) 210, a Home Subscriber Server (HSS)220, and an Operator's IP Services 222. The EPS can interconnect withother access networks, but for simplicity those entities/interfaces arenot shown. As shown, the EPS provides packet-switched services, however,as those skilled in the art will readily appreciate, the variousconcepts presented throughout this disclosure may be extended tonetworks providing circuit-switched services.

The E-UTRAN includes a number of evolved Node Bs including first evolvedNode Bs (eNBs) 206 and a second eNB 208. The second eNB 208 may be amacro base station that provides backhaul access to the first eNBs 206.The first eNBs provide user and control plane protocol terminationstoward the UE 202. The first eNBs 206 may be pico base stations that areconnected to the second eNB 208 via an X2 interface or other suitableconnections including a backhaul. The eNBs 206, 208 may also be referredto by those skilled in the art as a base station, a base transceiverstation, a radio base station, a radio transceiver, a transceiverfunction, a basic service set (BSS), an extended service set (ESS), orsome other suitable terminology. The first eNB 206 provides an accesspoint to the EPC 210 for a UE 202 via an access link. In this case, thefirst and second eNBs 206 and 208 are scheduling entities, and the UE isa subordinate entity. Examples of UEs 202 include a cellular phone, asmart phone, a session initiation protocol (SIP) phone, a laptop, apersonal digital assistant (PDA), a satellite radio, a globalpositioning system, a multimedia device, a video device, a digital audioplayer (e.g., MP3 player), a camera, a game console, a wearable device,an Internet-of-Thing (IoT) device, or any other similar functioningdevice. The UE 202 may also be referred to by those skilled in the artas a mobile station, a subscriber station, a mobile unit, a subscriberunit, a wireless unit, a remote unit, a mobile device, a wirelessdevice, a wireless communications device, a remote device, a mobilesubscriber station, an access terminal, a mobile terminal, a wirelessterminal, a remote terminal, a handset, a user agent, a mobile client, aclient, or some other suitable terminology.

The second eNB 208 is connected by an S1 interface to the EPC 210. TheEPC 210 includes a Mobility Management Entity (MME) 212, other MMEs 214,a Serving Gateway 216, and a Packet Data Network (PDN) Gateway 218. TheMME 212 is the control node that processes the signaling between the UE202 and the EPC 210. Generally, the MME 212 provides bearer andconnection management. All user IP packets are transferred through theServing Gateway 216, which itself is connected to the PDN Gateway 218.The PDN Gateway 218 provides UE IP address allocation as well as otherfunctions. The PDN Gateway 218 is connected to the Operator's IPServices 222. The Operator's IP Services 222 include the Internet, theIntranet, an IP Multimedia Subsystem (IMS), and a PS Streaming Service(PSS).

FIG. 3 is a diagram illustrating an example of an access network inaccordance with an aspect of the disclosure. In some examples, theaccess network of FIG. 3 may be a part of as an integrated access andbackhaul (IAB) network. In this example, the access network 300 isdivided into a number of regions or cells 302. One or more lower powerclass scheduling entities such as eNBs 308, 312 may have cellularregions 310, 314, respectively, that overlap with one or more of thecells 302. The lower power class eNBs 308, 312 may be femto cells (e.g.,home eNBs (HeNBs)), pico cells, or micro cells. A higher power classscheduling entity, for example a macro eNB 304, is assigned to a cell302 and may be configured to provide an access point to the EPC 210 (seeFIG. 2) or other networks for all the UEs 306 (subordinate entity) inthe cell 302. In some examples, a high power class macro eNB 304 onlycommunicates with the pico or lower power class eNBs. There is nocentralized controller in this example of an access network 300, but acentralized controller may be used in alternative configurations. TheeNBs 304, 308, and 312 may be responsible for all radio relatedfunctions including radio bearer control, admission control, mobilitycontrol, scheduling, security, and connectivity to the serving gateway216 (see FIG. 2).

The modulation and multiple access scheme employed by the access network300 may vary. For example, the variance may depend on the particulartelecommunications standard being deployed. In LTE applications, OFDM isused on the DL and SC-FDMA is used on the UL to support both frequencydivision duplexing (FDD) and time division duplexing (TDD). In oneparticular example, the access network 300 or some of its cell regionsmay be configured to support IAB TDD UL and DL.

As those skilled in the art will readily appreciate from the detaileddescription to follow, the various concepts presented herein are wellsuited for LTE applications. However, these concepts may be readilyextended to other telecommunication standards employing other modulationand multiple access techniques. By way of example, these concepts may beextended to Evolution-Data Optimized (EV-DO). EV-DO is an air interfacestandard promulgated by the 3rd Generation Partnership Project 2 (3GPP2)as part of the CDMA2000 family of standards and employs CDMA to providebroadband Internet access to mobile stations. These concepts may also beextended to Universal Terrestrial Radio Access (UTRA) employingWideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA;Global System for Mobile Communications (GSM) employing TDMA; andEvolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSMare described in documents from the 3GPP organization. CDMA2000 isdescribed in documents from the 3GPP2 organization. The actual wirelesscommunication standard and the multiple access technology employed willdepend on the specific application and the overall design constraintsimposed on the system.

FIG. 4 is a block diagram of a scheduling entity 410 in communicationwith a subordinate entity 450 in accordance with an aspect of thedisclosure. In various aspects of the disclosure, the scheduling entity410 may be a macro base station or a pico base station, and thesubordinate entity 450 may be a UE similar to those illustrated in anyof FIGS. 1-3 and 5. In the downlink (DL), upper layer packets from thecore network are provided to a controller/processor 475. In the DL, thecontroller/processor 475 may provide header compression, ciphering,packet segmentation and reordering, multiplexing between logical andtransport channels, and radio resource allocations to the subordinateentity 450 based on various priority metrics. The controller/processor475 may also be responsible for HARQ operations, retransmission of lostpackets, and signaling to the UE 450.

The TX processor 416 implements various signal processing functions forthe L1 layer (i.e., physical layer). The signal processing functionsincludes coding and interleaving to facilitate forward error correction(FEC) at the UE 450 and mapping to signal constellations based onvarious modulation schemes (e.g., binary phase-shift keying (BPSK),quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK),M-quadrature amplitude modulation (M-QAM)). The coded and modulatedsymbols are then split into parallel streams. Each stream is then mappedto an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot)in the time and/or frequency domain, and then combined together using anInverse Fast Fourier Transform (IFFT) to produce a physical channelcarrying a time domain OFDM symbol stream. The OFDM stream is spatiallyprecoded to produce multiple spatial streams. Channel estimates from achannel estimator 474 may be used to determine the coding and modulationscheme, as well as for spatial processing. The channel estimate may bederived from a reference signal and/or channel condition feedbacktransmitted by the UE 450. Each spatial stream is then provided to adifferent antenna 420 via a separate transmitter 418TX. Each transmitter418TX modulates an RF carrier with a respective spatial stream fortransmission.

At the UE 450, each receiver 454RX receives a signal through itsrespective antenna 452. Each receiver 454RX recovers informationmodulated onto an RF carrier and provides the information to thereceiver (RX) processor 456.

The RX processor 456 implements various signal processing functions ofthe L1 layer. The RX processor 456 performs spatial processing on theinformation to recover any spatial streams destined for the UE 450. Ifmultiple spatial streams are destined for the UE 450, they may becombined by the RX processor 456 into a single OFDM symbol stream. TheRX processor 456 then converts the OFDM symbol stream from thetime-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe eNB 410. These soft decisions may be based on channel estimatescomputed by the channel estimator 458. The soft decisions are thendecoded and deinterleaved to recover the data and control signals thatwere originally transmitted by the eNB 410 on the physical channel. Thedata and control signals are then provided to the controller/processor459.

In the UL, the control/processor 459 may provide demultiplexing betweentransport and logical channels, packet reassembly, deciphering, headerdecompression, control signal processing to recover upper layer packetsfrom the core network. The upper layer packets are then provided to adata sink 462, which represents all the protocol layers above the L2layer. Various control signals may also be provided to the data sink 462for L3 processing. The controller/processor 459 is also responsible forerror detection using an acknowledgment (ACK) and/or negativeacknowledgment (NACK) protocol to support HARQ operations.

In the uplink (UL), a data source 467 is used to provide upper layerpackets to the controller/processor 459. The data source 467 representsall protocol layers above the L2 layer (L2). Similar to thefunctionality described in connection with the DL transmission by theeNB 410, the controller/processor 459 implements the L2 layer for theuser plane and the control plane by providing header compression,ciphering, packet segmentation and reordering, and multiplexing betweenlogical and transport channels based on radio resource allocations bythe eNB 410. The controller/processor 459 is also responsible for HARQoperations, retransmission of lost packets, and signaling to the eNB410.

Channel estimates derived by a channel estimator 458 from a referencesignal or feedback transmitted by the eNB 410 may be used by the TXprocessor 468 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 468 are provided to different antenna 452 via separatetransmitters 454TX. Each transmitter 454TX modulates an RF carrier witha respective spatial stream for transmission.

The UL transmission is processed at the eNB 410 in a manner similar tothat described in connection with the receiver function at the UE 450.Each receiver 418RX receives a signal through its respective antenna420. Each receiver 418RX recovers information modulated onto an RFcarrier and provides the information to an RX processor 470. The RXprocessor 470 implements the L1 layer.

In the UL, the control/processor 459 may provide demultiplexing betweentransport and logical channels, packet reassembly, deciphering, headerdecompression, control signal processing to recover upper layer packetsfrom the UE 450. Upper layer packets from the controller/processor 475may be provided to the core network. The controller/processor 459 isalso responsible for error detection using an ACK and/or NACK protocolto support HARQ operations.

In one aspect of the disclosure, the processing system 114 described inrelation to FIG. 1 may include some or all components of the schedulingentity 410. In particular, the processing system 114 may include the TXprocessor 416, the RX processor 470, and the controller/processor 475.In one aspect of the disclosure, the processing system 114 described inrelation to FIG. 1 may include some or all components of the subordinateentity 450. In particular, the processing system 114 may include the TXprocessor 468, the RX processor 456, and the controller/processor 459.

FIG. 5 is a diagram illustrating an example of an integrated access andbackhaul (IAB) network 500 configured to utilize opportunistic accesslink/backhaul scheduling in accordance with an aspect of the disclosure.The wireless IAB network 500 may include any numbers of schedulingentities (e.g., macro base stations, pico base stations) and UEs. Inthis example, a macro base station may be a macro eNB, and a pico basestation may be a pico eNB. In the IAB network 500, a macro eNB 502 mayestablish backhaul connections 508 with one or more pico eNBs 504. Eachpico eNB 504 may establish access link 510 connections with one or moreUEs 506. Each connection may include one or more carriers or channelsfor facilitating communication between base stations and UEs. The macroeNB, pico eNBs, and UEs illustrated in FIG. 5 may be any of the eNBs andUEs illustrated in FIGS. 1-4 discussed above. In some aspects of thedisclosure, there may be additional layers of eNBs or base stationsbetween the macro eNB 502 and the pico eNB 504. In one example, eachlayer between the macro eNB 502 and pico eNB 504 may include a basestation or eNB configured to relay communication between the macro eNB502 and pico eNB 504. In some examples, one or more backhauls and accesslinks may be assigned common transmission resources for opportunisticaccess link and/or backhaul communication. Some examples of transmissionresources include time slots, frequency spectrum, channels, carriers,spreading codes, scrambling codes.

FIG. 6 is a diagram illustrating an example of a time division duplexing(TDD) frame structure 600 in accordance with an aspect of thedisclosure. The TDD frame structure 600 illustrates an example of thetime division of backhaul subframes and access link subframes. TDD canbe utilized in the IAB network of FIG. 5 or other TDD networks. In theIAB network 500, for example, the backhaul communication between a macroeNB 502 and a pico eNB 504 may be time-divided into UL subframes and DLsubframes utilizing the TDD frame structure 600. Similarly, the accesslink communication between a pico eNB 504 and a UE 506 may betime-divided into UL subframes and DL subframes utilizing the TDD framestructure 600.

In the downlink (DL) time slots, backhaul DL traffic 602 and access linkDL traffic 604 may be time interleaved in different time slots orsubframes. Similarly, in the uplink (UL) time slots, the backhaul ULtraffic 606 and access link UL traffic 608 may be time interleaved indifferent time slots or subframes. While FIG. 6 illustrates a particulartime interleaving order for the backhaul traffic and access linktraffic, other combinations are possible. For example, the backhaul DLtraffic 602 and access link DL traffic 604 may be reversed in timesequence. Similarly, the backhaul UL traffic 606 and access link ULtraffic 608 may be reversed in time sequence. In some aspects of thedisclosure, the interleaving order of the backhaul traffic and accesslink traffic may be different or the same for the DL and UL time slots.In some aspects/embodiments of the disclosure, the interleaving order ofthe backhaul traffic and access link traffic may be different ordynamically changed for different frames. In some examples, the timeslots assigned to the backhaul traffic and access link traffic may bedifferent or the same based on various factors and designs.

Various aspects of the present disclosure provide a wirelesscommunications system in which an access link can opportunisticallyutilize the same transmission resource assigned to a backhaul such thataccess link transmission and backhaul transmission may occursimultaneously. For example, in an IAB network 500, the access link andthe backhaul may utilize the same frequency spectrum (e.g., same carrieror channel) for communication in the same UL and/or DL time slot. In oneaspect of the disclosure, the access link may opportunistically utilizethe same transmission resource of the backhaul when the interferencefrom such opportunistic access link transmission will not causesignificant or undesirable interference to the backhaul. The access linktransmission is opportunistic when the access link transmission occursunder certain predetermined conditions, while it is not originallyscheduled. For example, opportunistic transmission may occurirregularly, and may be bursty, dynamic, and/or variable. That is, anopportunistic access link transmission may not have a predeterminedschedule in general. For example, an opportunistic access linktransmission may be scheduled irregularly. The opportunistic access linktransmission may utilize the transmission resource (e.g., time andfrequency resources) originally scheduled for the backhaul link at thesame time, for example, in the same time slot or time frame for uplinkor downlink transmission. In some examples, an opportunistic access linktransmission may utilize a full time slot or only a portion of a timeslot scheduled for a backhaul link.

FIG. 7 is a diagram illustrating examples of frame structures foropportunistic access link or backhaul scheduling in accordance with anaspect of the disclosure. A frame structure 700 may be utilized toschedule backhaul and opportunistic access link traffic. In an IABnetwork 500, the backhaul communication between a macro eNB 502 and apico eNB 504 may be time-divided into UL subframes and DL subframesutilizing the frame structure 700. Similarly, the access linkcommunication between a pico eNB 504 and a UE 506 may be time-dividedinto UL subframes and DL subframes utilizing the frame structure 700. Invarious aspects of the disclosure, an access link may opportunisticallyutilize the same transmission resource (e.g., time and frequencyresources) assigned to a backhaul when the interference from theopportunistic access link will not cause significant or undesirableamount of interference to the backhaul. In one example, an access linkis opportunistic when the access link traffic (UL and/or DL) isselectively scheduled under certain conditions (e.g., predeterminedconditions) in a time slot originally assigned only to the backhaul, andthe access link traffic and backhaul link traffic may occursimultaneously during at least a portion of the same time slot orsubframe.

Referring to FIG. 7, a first time slot 702 or subframe may be assigned(or reserved/scheduled) to backhaul DL traffic, and a second time slot704 or subframe may be assigned to access link DL traffic. In one aspectof the disclosure, the access link traffic (DL or UL) may beopportunistically scheduled in the time slot 702 that is originallyassigned or scheduled to the backhaul when the access link traffic willnot cause significant undesirable interference to the backhaul DL. Athird time slot 706 or subframe may be assigned to backhaul UL traffic,and a fourth time slot 708 or subframe may be assigned to access link ULtraffic. In one aspect of the disclosure, the access link traffic (DL orUL) may be opportunistically scheduled in the third time slot 706originally assigned or scheduled only to the backhaul when the accesslink traffic will not cause significant undesirable interference to thebackhaul UL. In general, an opportunistic access link may occur in afirst time period (e.g., time slots 702 and 704) different from a secondtime period (e.g., time slots 704 and 708) that is regularly scheduledfor the access link traffic. For example, an opportunistic access linkmay be scheduled in a time period (e.g., 702 and 706) scheduled for abackhaul link between a scheduling entity and an UE.

In other aspects of the disclosure, the concept of an opportunisticaccess link, may be extended to an opportunistic backhaul as illustratedin a subframe 710. The subframe structure 710 may be utilized toschedule backhaul and access link traffic in an IAB network 500. Abackhaul may opportunistically utilize the same transmission resource(e.g., time and frequency resources) originally assigned only to anaccess link when the interference from the opportunistic backhaul willnot cause significant or undesirable amount of interference to theaccess link. In one example, the backhaul is opportunistic when thebackhaul traffic (UL and/or DL) is selectively scheduled under certainconditions (e.g., predetermined conditions) in a time slot 712 that isoriginally assigned only to the access link, and the access link traffic(UL or DL) and opportunistic backhaul traffic may occur simultaneouslyduring at least a portion of the same time slot or subframe.

The present disclosure is not limited to the subframe examples of FIG.7. In other aspects of the disclosure, other frame structures may beused for opportunistic access link/backhaul scheduling. In someexamples, opportunistic access link traffic may be scheduled only in abackhaul DL time slot or a backhaul UL time slot. In some examples,opportunistic access link traffic may be only UL traffic or DL traffic.Similar variations may be applied to the opportunistic backhaul traffic.

Two examples of backhaul and access link traffic scheduling (orpatterns) are synchronized scheduling and cross-synchronized scheduling.FIG. 8 is a diagram illustrating two examples of synchronized schedulingin accordance with some aspects of the disclosure. In synchronizedscheduling, the access link traffic and backhaul traffic occur in thesame direction (e.g., UL or DL). In a DL example, the backhaul traffic802 (macro eNB-to-pico eNB1) and the access link traffic 804 (picoeNB2-to-UE1) are both in the DL traffic direction. The DL transmissionfrom the macro eNB may cause interference to the UE1. In a UL example,the access link traffic 806 (UE1-to-pico eNB2) and the backhaul traffic808 (pico eNB1-to-macro eNB) both occur in the UL direction. The ULtransmission from the UE1 may cause interference to the macro eNB. Inthis example, the access links 804, 806 and backhauls 802, 808 may bescheduled to utilize the same transmission resource (e.g., samecarrier/channel or time slot).

FIG. 9 is a diagram illustrating two examples of cross-synchronizedscheduling in accordance with some aspects of the disclosure. Incross-synchronized scheduling, the access link traffic and backhaultraffic are scheduled to transmit in different directions. In oneexample, the backhaul traffic 902 (macro eNB-to-pico eNB1) and theaccess link traffic 904 (UE2-to-pico eNB2) are respectively scheduled inthe DL and UL directions. In this case, the DL backhaul transmissionfrom the macro eNB may cause interference to the pico eNB2, and the ULaccess link transmission from the UE2 may cause interference to the picoeNB1. In another example, the access link traffic 906 (pico eNB2-to-UE2)and the backhaul traffic 908 (pico eNB1-to-macro eNB) are respectivelyscheduled in the DL and UL directions. The DL access link transmissionfrom the pico eNB2 may cause interference to the macro eNB, and the ULbackhaul transmission from the pico eNB1 may cause interference to theUE2. In this example, the access links 904, 906 and backhauls 902, 908may be scheduled to use the same transmission resource (e.g., frequencyspectrum and time slot).

In the backhaul DL example of FIG. 8, the interference between thebackhaul traffic 802 and the access link traffic 804 is from the picoeNB 2 to the pico eNB 1, and from the macro eNB to the UE. In thebackhaul UL example of FIG. 8, the interference between the backhaultraffic 808 and the access link traffic 806 is from the pico eNB 1 tothe pico eNB 2, and from the UE to the macro eNB. In the backhaul DLexample of FIG. 9, the interference between the backhaul traffic 902 andthe access link traffic 904 is from the UE to the pico eNB 1, and fromthe macro eNB to the pico eNB 2. In the backhaul UL example of FIG. 9,the interference between the backhaul traffic 908 and access linktraffic 906 is from the pico eNB 1 to the UE, and from the pico eNB 2 tothe macro eNB. In general, the base stations (e.g., pico eNB 1, pico eNB2, and macro eNB) have greater transmit power than the UEs, and thedistance between nearby pico eNBs may be smaller than the distancebetween the pico eNBs and the macro eNB. In this case,cross-synchronized scheduling may reduce the interference between thepico eNBs. Therefore, cross-synchronized scheduling of backhaul trafficand access link traffic may reduce or minimize the interference betweenbackhaul traffic and opportunistic access link traffic.

FIG. 10 is a flow chart illustrating an opportunistic access linkscheduling method 1000 operable in a wireless network in accordance withan aspect of the disclosure. The method may be performed by a schedulingentity, for example, a pico eNB or base station illustrated in any ofFIGS. 1-5, 8 and/or 9. In one aspect of the disclosure, a schedulingentity (pico eNB) may utilize a backhaul traffic block 120, an accesslink traffic block 122, and an IAB block 124 illustrated in FIG. 1 toperform the scheduling method 1000. In one particular example, a picoeNB (e.g., a pico eNB 2 of FIG. 8 or 9) may perform the access linkscheduling method 1000 to schedule an access link in an IAB network 500(see FIG. 5). At block 1002, the method may utilize, at a schedulingentity (e.g., pico eNB 2), the backhaul traffic block 120 to determine afirst direction of a backhaul link traffic (first data traffic) betweena first scheduling entity and a second scheduling entity. For example,the first scheduling entity may be a macro eNB, and the secondscheduling entity may be a pico eNB 1, as shown in FIG. 8 or 9.

FIG. 11 is a flow chart illustrating a method 1100 for determining thebackhaul traffic direction between the first scheduling entity andsecond scheduling entity. In one example, at block 1102, the schedulingentity (e.g., pico eNB 2) may receive system information from the firstscheduling entity (macro eNB) through a suitable communication channelor method. In one example, the information may be included in one ormore system information blocks (SIBs) broadcasted by the macro eNB usinga control channel. At block 1104, the scheduling entity may determinethe backhaul link traffic direction based on the received systeminformation. For example, the received system information may containcertain data that indicate the direction of the backhaul link trafficbetween the macro eNB (first scheduling entity) and pico eNBs (secondscheduling entity).

Referring back to FIG. 10, at block 1004, the method may utilize theaccess link traffic block 122 to determine a second direction of anaccess link traffic (second data traffic) between the scheduling entity(e.g., pico eNB 2) and a user equipment (UE) based on the firstdirection of the backhaul link traffic to reduce potential interferencethat may be caused by the access link traffic. For example, thescheduling entity may be the pico eNB 2 of FIG. 8 or 9, and the UE maybe the UE of FIG. 8 or 9. In one example, cross-synchronized scheduling(see FIG. 9) may be used to reduce the interference that may be causedby the access link.

FIG. 12 is a flow chart illustrating a method 1200 for determining anopportunistic access link traffic direction in accordance with an aspectof the disclosure. In one example, the method 1200 may be operable atblock 1004 of FIG. 10. At decision block 1202, a scheduling entity(e.g., pico eNB 2 of FIG. 9) determines a traffic direction of abackhaul. For example, the backhaul may be a backhaul link between amacro eNB and a pico eNB 1 as shown in FIG. 9. If it is determined thatthe backhaul direction is DL, the method proceeds to block 1204;otherwise, the method proceeds to block 1206. At block 1204, thescheduling entity sets the opportunistic access link traffic to be UL.At block 1206, the scheduling entity sets the opportunistic access linktraffic to be DL. In this particular example, the scheduling entity setsthe opportunistic access link traffic direction to be opposite to thatof the backhaul in the same time slot. In other aspects of thedisclosure, the backhaul traffic and the access link traffic may be setto the same direction.

Furthermore, referring back to FIG. 10, at block 1006, the method 1000may utilize the IAB block 124 to opportunistically transmit or receivethe access link traffic, at the scheduling entity, in the seconddirection utilizing at least one of the same transmission resource ofthe backhaul link traffic. Examples of the transmission resource mayinclude a frequency spectrum (channel or carrier), a time slot (orsubframe) of a TDD system, a spreading code, and other resourcescommonly used for access link and backhaul link transmissions. Thescheduling entities may communicate with each other via one or morechannels including the backhauls between the scheduling entities. Forexample, the scheduling entity (e.g., pico eNB 2) may determine thetraffic direction between the first scheduling entity (e.g., macro eNB)and second scheduling entity (e.g., pico eNB 1) based on systeminformation blocks received from the first scheduling entity.

FIG. 13 is a flow chart illustrating a method 1300 of opportunisticaccess link transmission in accordance with an aspect of the disclosure.In one example, the method 1300 may be operable at block 1006 of FIG.10. Assuming, it has been determined that in a backhaul time slot, anaccess link may be utilized opportunistically. At block 1302, ascheduling entity (e.g., a pico eNB 2 of FIG. 9) may measure one or morechannels (e.g., pilots or other suitable signals) of a macro eNB. Atblock 1304, the scheduling entity determines the potential interferenceat the macro eNB that may be caused by the opportunistic access link. Inone example, the macro eNB may transmit a signal-to-noise ratio (SNR)value of its own uplink, so that the scheduling entity may calculate asignal-to-interference ratio (SIR) at the macro eNB, and thus maydetermine if it may cause too much interference to the backhaul when theaccess link transmission occurs. If the potential interference is lessthan a predetermined threshold, the access link may opportunisticallytransmit at block 1306; otherwise, the opportunistic access link is notscheduled.

In other aspects of the disclosure, the concept of the opportunisticaccess link scheduling as described above may be implemented on thebackhaul. An opportunistic backhaul may be scheduled to take place usingthe same transmission resource of an access link simultaneously if theopportunistic backhaul will not cause significant or undesirableinterference to the access link.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. The accompanyingmethod claims present elements of the various steps in a sample order,and are not meant to be limited to the specific order or hierarchypresented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed under the provisions of 35U.S.C. § 112(f), unless the element is expressly recited using thephrase “means for” or, in the case of a method claim, the element isrecited using the phrase “step for”.

What is claimed is:
 1. A method of wireless communication operable at afirst pico base station communicatively connected with a macro basestation, comprising: determining a first direction of a backhaul linktraffic between the macro base station and a second pico base station,wherein the first direction comprises an uplink direction or a downlinkdirection; determining a second direction of an access link trafficbetween the first pico base station and a user equipment (UE) based onthe first direction of the backhaul link traffic, wherein the seconddirection comprises an uplink direction or a downlink direction that isdifferent from the first direction; and transmitting or receiving, atthe first pico base station, the access link traffic in the seconddirection utilizing at least one of a same time and frequency resourcesof the backhaul link traffic.
 2. The method of claim 1, wherein thedetermining the second direction of the access link traffic comprises:determining the second direction to be an uplink or a downlink to reducean interference to the backhaul link traffic caused by the access linktraffic.
 3. The method of claim 1, wherein the transmitting or receivingthe access link traffic comprises: scheduling the access link traffic tobe transmitted or received simultaneously with the backhaul linktraffic; or scheduling the access link traffic to be transmitted orreceived in a time period scheduled for the backhaul link traffic. 4.The method of claim 1, wherein the transmitting or receiving the accesslink traffic comprises: scheduling the access link traffic to occur in afirst time period different from a second time period that is regularlyscheduled for the access link traffic.
 5. The method of claim 1, whereinthe transmitting or receiving the access link traffic comprises:transmitting or receiving the access link traffic in a time periodscheduled for a backhaul link traffic between the first pico basestation and the UE.
 6. A first pico base station communicativelyconnected with a macro base station for wireless communication,comprising: means for determining a first direction of a backhaul linktraffic between the macro base station and a second pico base station,wherein the first direction comprises an uplink direction or a downlinkdirection; means for determining a second direction of an access linktraffic between the first pico base station and a user equipment (UE)based on the first direction of the backhaul link traffic, wherein thesecond direction comprises an uplink direction or a downlink directionthat is different from the first direction; and means for transmittingor receiving the access link traffic in the second direction utilizingat least one of a same time and frequency resources of the backhaul linktraffic.
 7. The first base station of claim 6, wherein the means fordetermining the second direction of the access link traffic isconfigured to: determine the second direction to be an uplink or adownlink to reduce an interference to the backhaul link traffic causedby the access link traffic.
 8. The first base station of claim 6,wherein the means for transmitting or receiving the access link trafficis configured to: schedule the access link traffic to be transmitted orreceived simultaneously with the backhaul link traffic; or schedule theaccess link traffic to be transmitted or received in a time periodscheduled for the backhaul link traffic.
 9. The first base station ofclaim 6, wherein the means for transmitting or receiving the access linktraffic is configured to: schedule the access link traffic to occur in afirst time period different from a second time period that is regularlyscheduled for the access link traffic.
 10. The first base station ofclaim 6, wherein the means for transmitting or receiving the access linktraffic is configured to: transmit or receive the access link traffic ina time period scheduled for a backhaul link traffic between the firstpico base station and the UE.
 11. A non-transitory computer-readablemedium comprising computer executable code for causing a first pico basestation communicatively connected with a macro base station, to:determine a first direction of a backhaul link traffic between the macrobase station and a second pico base station, wherein the first directioncomprises an uplink direction or a downlink direction; determine asecond direction of an access link traffic between the first pico basestation and a user equipment (UE) based on the first direction of thebackhaul link traffic, wherein the second direction comprises an uplinkdirection or a downlink direction that is different from the firstdirection; and transmit or receive the access link traffic in the seconddirection utilizing at least one of a same time and frequency resourcesof the backhaul link traffic.
 12. The non-transitory computer-readablemedium of claim 11, wherein for determining the second direction of theaccess link traffic, the executable code causes the first base stationto: determine the second direction to be an uplink or a downlink toreduce an interference to the backhaul link traffic caused by the accesslink traffic.
 13. The non-transitory computer-readable medium of claim11, wherein for transmitting or receiving the access link traffic, theexecutable code causes the first base station to: schedule the accesslink traffic to be transmitted or received simultaneously with thebackhaul link traffic; or schedule the access link traffic to betransmitted or received in a time period scheduled for the backhaul linktraffic.
 14. The non-transitory computer-readable medium of claim 11,wherein for transmitting or receiving the access link traffic, theexecutable code causes the first base station to: schedule the accesslink traffic to occur in a first time period different from a secondtime period that is regularly scheduled for the access link traffic. 15.The non-transitory computer-readable medium of claim 11, wherein fortransmitting or receiving the access link traffic, the executable codecauses the first base station to: transmit or receive the access linktraffic in a time period scheduled for a backhaul link traffic betweenthe first pico base station and the UE.
 16. A first pico base stationfor wireless communication, comprising: a communication interfaceconfigured for wireless communication with a macro base station; amemory comprising executable code; and a processing system operativelycoupled to the communication interface and memory, wherein theprocessing system is configured by the executable code to: determine afirst direction of a backhaul link traffic between the macro basestation and a second pico base station, wherein the first directioncomprises an uplink direction or a downlink direction; determine asecond direction of an access link traffic between the first pico basestation and a user equipment (UE) based on the first direction of thebackhaul link traffic, wherein the second direction comprises an uplinkdirection or a downlink direction that is different from the firstdirection; and transmit or receive the access link traffic in the seconddirection utilizing at least one of a same time and frequency resourcesof the backhaul link traffic.
 17. The first base station of claim 16,wherein the processing system is further configured to: determine thesecond direction to be an uplink or a downlink to reduce an interferenceto the backhaul link traffic caused by the access link traffic.
 18. Thefirst base station of claim 16, wherein for transmitting or receivingthe access link traffic, the processing system is further configured to:schedule the access link traffic to be transmitted or receivedsimultaneously with the backhaul link traffic; or schedule the accesslink traffic to be transmitted or received in a time period scheduledfor the backhaul link traffic.
 19. The first base station of claim 16,wherein for transmitting or receiving the access link traffic, theprocessing system is further configured to: schedule the access linktraffic to occur in a first time period different from a second timeperiod that is regularly scheduled for the access link traffic.
 20. Thefirst base station of claim 16, wherein for transmitting or receivingthe access link traffic, the processing system is further configured to:transmit or receive the access link traffic in a time period scheduledfor a backhaul link traffic between the first pico base station and theUE.